What do you need to know? Different traders buy different goods. The PDA tells you which factories produce which goods. In most cases you will need to do the unlock mission for a factory, which will require goods, in order to trade with them.
Aside from Tech Items, Furnishings, Tribal goods, all of which can be obtained from various forms of POIs, various other items can also be obtained as loot. Then there is always mining and trading ore of ingots. You just have to learn which traders want which items and which are the more valuable things to trade.

Dude explore. It's the point of the whole game.

I do explore, but I am a casual gamer. I didn't want to spend a month just searching for all of the places I should be trading. I have spent hours just exploring all of the planets in one system. There are a lot of systems out there. I was just looking for suggestions of what I should be looking for and where to start.

A good starting point is the Empyriopedia (F1)

Originally posted by Dratcha:

I do explore, but I am a casual gamer. I didn't want to spend a month just searching for all of the places I should be trading. I have spent hours just exploring all of the planets in one system. There are a lot of systems out there. I was just looking for suggestions of what I should be looking for and where to start.

No body can provide that. The stars are RNG determined when you start a game. The system contents for a star are RNG detemined when you warp to a system. The sector contents are RNG detemined when you warp to a planetary sector. SInce all the factories/traders etc are RNG from lists based on star and planetary types, no one can tell you where you will find X.

Originally posted by nevryn:

What do you need to know? Different traders buy different goods. The PDA tells you which factories produce which goods. In most cases you will need to do the unlock mission for a factory, which will require goods, in order to trade with them.
Aside from Tech Items, Furnishings, Tribal goods, all of which can be obtained from various forms of POIs, various other items can also be obtained as loot. Then there is always mining and trading ore of ingots. You just have to learn which traders want which items and which are the more valuable things to trade.

When you unlock a specific trader does that unlock all instances of that trader or do you have to unlock him everywhere he occurs.

You have to unlock each individual factory.
You can also use the Starfreight Services on a GIN Console to pay to complete a factory unlock mission if you aren't able to (or are too lazy to) get the requested items yourself.

Trade can make you quite wealthy in this game. Start with the local traders and do their assigned missions to unlock their stores. That's when things really pick up. If you can manage to unlock ice mining, you can make you way to Solitude and stock up on Rich Ice and sell to Ice vendors in Polaris, Trade Federation and Colonist space (and Pirate and Xerox if by some miracle you are neutral). When you get enough credits, you can do the orbital trade factories. Optronics and Robotics are huge 32K size, 1M credit shipments but can net 150K profit when you deliver to Advanced Component factories in Trade Federation. Pick up a new shipment from them and deliver to Polaris and Colonist space and .... by the time you get home you find yourself anywhere from 2 to 5 M credits in profit. Pretty nice. Be aware however that your trade ship will likely attract Warlord and Pirate raiders so be prepared to either fight or run. And do PoI or missions to get those Navigation data items to increase your warp range. Having 100 ly jump range makes the trade missions much easier. Also, unlock the micro warp capability. When you arrive in a trade sector you might be 10-20 km from your destination and micro warp can help. I sometimes wonder if anyone in this game has actually made it to 1 B credits. I tried in RE1 and made it to 200 M but then RE2 came out. So, might try again ....